Structure-Composition-Property Relationships in Complex Intermetallic Phases: Experimental and Theoretical Studies

该项目涉及结合实验和理论方法来寻找和研究新型复杂金属间化合物，这些化合物将具有有趣的结构和磁性特性，并可能应用于环保制冷剂和磁传感器。 目标化合物由活性金属（钠、钾、锶、钡和稀土）以及磁性元素（铁、钴、镍）和后过渡元素（铝、锗、铟、硅和锗）的组合组成：此类化合物应采用涉及金属簇的精美复杂结构，这些金属簇通过优化金属-金属键合进行控制，而且还显示出通过与其轨道重叠耦合的交换相互作用提供有趣的磁性的排列，即磁热效应和磁致伸缩。 这些研究将使人们对金属间化合物如何形成以及控制磁系统结构的因素有基本的了解。如果我们成功地优化磁热效应，我们可能会找到一种在接近室温时有效制冷的材料，该材料对环境友好且经济可行。 年轻科学家将学习空气敏感、高温合成、衍射和电子理论计算方面的最先进技术。该项目旨在形成和研究不同金属元素之间的新化合物，称为金属间化合物。 这些新化合物的一个组成部分将是磁性元素，如铁或钴，这将使我们能够探索新化合物作为替代氯氟烃的制冷材料（“磁制冷”）。 此类化合物利用磁性来进行制冷，这是一种更有效的过程，而且材料也比现有物质更环保。 这项研究的一个重要基本目标是了解哪些因素控制金属间化合物的形成和生长，以便我们最终能够设计出具有特定电或磁性能的材料。 我们计划通过仔细合成、测量晶体中元素的结构和排列、确定其磁性以及计算机建模来寻找新的金属间化合物来实现这一目标。 参与该项目的学生将学习金属合成、表征和理论建模方面的最先进技术。 该项目结合了实验和理论工作，将为这些学生在学术界（培训下一代科学家和工程师）或工业界（他们可以应用新技术来制造新材料）的职业生涯做好准备。

This project involves combining experimental and theoretical approaches to search for and study new complex intermetallic compounds that will have interesting structural and magnetic properties with possible applications to environmentally friendly refrigerants and magnetic sensors. The compounds targeted consist of active metals (sodium, potassium, strontium, barium, and rare-earths) with combinations of magnetic elements (iron, cobalt, nickel) and the post-transition elements (aluminium, germanium, indium, silicon and germanium): such compounds should adopt beautifully complex structures involving metal clusters that are controlled by optimizing metal-metal bonding, but also showing arrangements giving interesting magnetic properties through exchange interactions coupled to their orbital overlaps, i.e., magnetocaloric effects and magnetostriction. These studies will lead to fundamental understanding of how intermetallic compounds form and the factors that control structure in magnetic systems. If we are successful to optimize the magnetocaloric effect, we may find a material effective for refrigeration near room temperature that is environmentally benign and economically feasible. Young scientists will learn state-of-the-art techniques in air-sensitive, high temperature synthesis, diffraction and in the theoretical calculation of electronic This project is designed to form and study new compounds between different metallic elements, called intermetallic compounds. One component of these new compounds will be magnetic elements, like iron or cobalt, which will allow us to probe new compounds to serve as materials for refrigeration in place of chlorofluorocarbons ("magnetic refrigeration"). Such compounds use magnetism to perform refrigeration, which is a more efficient process and the materials are also more environmentally friendly than current substances. An important fundamental goal of this research is to understand what factors control the formation and growth of intermetallic compounds, so that we may ultimately be able to design materials with specific electrical or magnetic properties. We plan to achieve this goal by searching for new intermetallic compounds through careful synthesis, through measurement of the structure and arrangement of elements in their crystals, through determination of their magnetic properties and through computer modeling. Students involved with this project will learn state-of-the-art techniques in metals synthesis, characterization and theoretical modeling. This project, which combines experimental and theoretical work, will prepare these students for careers in academia (for training our next generation of scientists and engineers) or in industry (where they can apply new techniques for the fabrication of new materials).